Method of making stay bolts



, July 7, 1925. 1,544,731

G. H. EMERSON METHOD OF MAKING STAY BOLTS Filed Fe 16, 1923 Patented July 7, 1925.

- 1,544,731 PATENT OFFICE.

enonsn H. nnnnsonor BALTIMORE, AR LA D.

' YMETHOD-OFTMAKING STAY BoL'rs.

Application filed February 16,, 1923. Serial No. 619,338.

To all whom it may concern."

Be it known that I, Gnonen H. EMERSON, a citizen ofthe United States, residing at Baltimore city, in the State of Maryland,

have invented certain new and useful Improvements in Methods of Making Stay Bolts; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to a method of making stay bolts for boilers.

Among the objects of my invention are To provide a stay bolt for boilers having high tensile strength and low transverse stiffness.

To provide a bolt havingthe above characteristics so constructed that all parts of said bolt exposed inthe water space of the boiler will be substantially of the same elec tric potential whereby electrolysis and quick deterioration of my improved bolt is prevented. I V I 7 To provide a method of forming my improved bolt in a cheap and practical manner.

Heretofore, when the ordinary bolts have been employed it has been necessary to make them of. considerable cross section to provide suficient tensile strength. Then the bolts are made of suflicient cross section to provide the needful tensile strength they then had considerable transverse stiffness so that as relative movements of the sheets of the boilers to which the ends of a stay bolt were secured took place a considerable strain was thrown upon the bolts which tended to loosen its fastening in the sheets or to shear the bolts.

Attempts have been made to overcome this defect by providing bolts of high tensile strength and small cross section with ends of enlarged cross section and formed of a different metal for securing in the boiler sheets. The defectof this construction has been that when such bolts were used in the water space of a boiler there were different electric potentials between the different metals, electrolysis resulted and the bolts soon deteriorated.

Other attempts made to provide bolts having high tensile strength and low transverse stiffness comprehended the use of a core having a high tensile strength and low transverse stiffness with a twisted casing around said bolt.

core having enlarged ends for securing in the boiler sheets.

The defect of this construction was that the casing of necessity was formed of fibrous metal and when the centre of the casing was.

boiler from the ends thereof; consequently,

electrolytic action took place with resulting rapid deterioration of the bolt.

By my improved method,- Izam enabled to provide a bolt having a core of high tensile strength and low transverse stiffness and in which all parts of the exposed metal when mounted in the water space of a boilerwill have substantially the same electric potential so that electrolytic action is entirely avoided.

In the drawings v Figure 1 represents the blank Of metal which is to form thecasing of my improved Fig. 2 shows the, casing or'strengthening member with the core of high tensile strength and low transverse stiffness mounted therein. I I V Fig. 3 shows the manner of applying the swages to the blank casing in order to close same in upon the shank of the core.

Fig. 4 shows the completed stay bolt as mounted in the boiler.

In the drawings:

5 represents the blank for the casing which is bored out as at 6. After said casing is bored the core or strengthening member 7 is introduced within said hole.

The core 7 is provided at the ends with balls 88 formed integrally with a shank 9 of a less diameter than the diameter ofsaid balls. The core 7 is preferablyconstructed of material having a high tensile strength and the shank 9 is made small in diameter so as to reduce the transverse stiffness thereof. The core 7 may be made of any of the alloy steels or other materials and may be treated by heat or otherwise in order to increase the tensile strength thereof.

After the core 7 is introduced in the hole 6, as just described, the blank 5 and core 7 are heated together and swages 1010 applied to said blank between the balls 88, thus closing the Walls of the hole 6 in upon the shank 9 as shown in Fig. 4.

After the blank 5 for the casing has been swaged ust described, it can be threaded lUO on the ends at the proper locations for attachment to the boiler plates 1111} It is to be noted that the shank 9 is to beef such a length that the balls 88 will be sufliciently distant from the facing ends of the threaded portions to provide adequate strength as shown in Fig. 1.

After the threading operation has been completed, the casing is to be. reduced in diameter, as shown in Fig. 1, in order to reduce the transverse stiltness of the casing.

Thus itwill be seen that I provide a bolt in which but a single metal is exposed to the water in the water space of a boiler and that the fibres of said metal are not twisted and are subjected during the construction of my improved bolt to a minimum of deformation.

While I have shown balls at the end of the shank 9, it is to be understood that these shapes may be varied.

It is also to be understood that changes may be made in my improved bolt and in the method for forming'the same Without departing from the spirit of my invention.

I claim 1. The herein described method of forming bolts having high tensile strength and low transverse stiffness which consists in drilling a hole partly through a blank of metal, then introducing within said hole a strengthening member comprising a shank and enlargements on the end of said shank larger in cross section than the cross section of 'said shank, and then swaging said blank 2. The hereindescribed method of forming bolts having high tensile strength and low transverse stiffness which consists in drilling a hole partly through a blank of metal, then introducing within said hole a strengthening member comprising a shank and enlargements on the end otsaid shank larger in cross section than the cross section of said shank, then swaging said blank between said enlargements until the walls of said hole are compressed against said shank and then turning said blank between said enlargements to a diameter smaller than the ends of said blank. 7

3. The herein described method of forming bolts having high tensile strength and low transverse stiffness which consists in drilling a hole partly through a blank of metal, then introducing within said hole a strengthening member comprising a shank and enlargements on the end of said shank larger in cross section than the cross section of said shank, then swaging said blank between said enlargements until the walls of said hole are compressed against said shank, then turning saidblank between said enlargements to a diameter smaller than the ends of said blank, and then threading said ends.

In testimony whereof I afliX my signature.

GEORGE H. EMERSON 

